1. Field of the Invention
The present invention relates to powershift transmissions for vehicles, e.g., work vehicles such as tractors and industrial equipment, and in particular, to transmissions of the type which can be altered easily to provide a variety of transmission ratios.
2. Description of the Related Art
Vehicles of various sizes require variously-sized transmissions Even vehicles of comparable sizes may need different gear ratios available to them, depending upon the working environment in which the vehicle will operate. For example, an agricultural tractor needs a large number of gears providing ground speeds between 2 and 5 kilometers per hour. In contrast, construction equipment typically does not need as many gear ratios in this range. However, the two pieces of equipment may otherwise be very similar. Indeed, early farm and construction equipment often was virtually identical.
As a result of these varying needs, it is not unusual to provide a variety of transmission options. Different transmissions provide different numbers or combinations of gear ratios, different transmission housings, and the like. Unfortunately, the larger the number of options, the greater the cost.